There are lots of options for filling raised beds, but do not use soil from the garden! For small raised beds there are some standard container type mixes with compost/vermiculite etc. For a large area consider getting bulk compost mix from a nursery - they usually diliver by the yard of material which covers a lot of garden space!. Big box stores also have bales of peat moss too which you can mix with bags of compost and a little vermiculite or perlite. A ratio of about 1 peat moss:1 compost:0.5 perlite/vermiculite works quite well